<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #app{
            width: 100px;
            height: 100px;
            border: 1px solid #333;
        }
    </style>
</head>
<body>
    <div id="app" draggable="true">
        可拖拽
    </div>
    <script>
        const app = document.getElementById("app")
        app.addEventListener("drag",throttle(function(e){
            console.log(e.offsetY);
        }))
        function throttle(fn,delay=500){
        
            let timer=null;
            return function(){
                if(timer){
                    return
                }
            },
            timer = setTimeout(()=>{
                // arguments是函数内部的一个对象，接收函数传递过来的参数
                console.log(arguments);
                fn.apply(this,arguments);
                timer =null;
            },delay)
        }
    </script>
</body>
</html>